How to acess and change solid OpenGL lights settings via python?
If you hover the color boxes with the mouse cursor you will find that the responsible python struct is UserSolidLight with the following properties


  base class — bpy_struct
  
  class bpy.types.UserSolidLight(bpy_struct) Light used for OpenGL
  lighting in solid draw mode
  
  diffuse_color Diffuse color of the OpenGL light
  
  Type: float array of 3 items in [0, inf], default (0.0, 0.0, 0.0)
  
  direction Direction that the OpenGL light is shining
  
  Type: float array of 3 items in [-inf, inf], default (0.0, 1.0, 0.0)
  
  specular_color Color of the light’s specular highlight
  
  Type: float array of 3 items in [0, inf], default (0.0, 0.0, 0.0)
  
  use
  Enable this OpenGL light in solid draw mode
  
  Type: boolean, default False


According to the Python API Documentation